There is increased need and market demand for communication systems that can operate in multiple frequency bands as well as using different modulation techniques. Additionally, the military is very interested in having the ability to operate securely at any frequency at any time. An important application area that requires adaptability and versatility are cellular communication systems. The software-defined radio (SDR) concept has long been recognized as a desirable system configuration for versatile communication systems and has been driving architectural innovation in recent years.
An important need in the development of the SDR concept is the integration of vastly different semiconductor technologies, including: Gallium Nitride (GaN), Indium Phosphide (InP), Gallium Arsenide (GaAs), silicon Complementary Metal-Oxide Semiconductor (CMOS), and Silicon-Germanium CMOS. While solid-state electronics have advanced in many ways over the years, differentiation due to very specific technical and/or economical requirements has resulted in significant process differences. Consequently, in the foreseeable future it is unlikely to see convergence between even silicon-based process sequences, let alone between non-Silicon process technologies. Therefore, the desire to integrate MEMS (microelectromechanical systems), various flavors of active Si, SiGe, GaAs, GaN, and InP technologies, along with passive electromagnetic, optical, acoustic, and magnetic processes is very much in need.